Generally, a secondary battery is a battery which can be repeatedly used through charging and discharging. A secondary battery that is formed of one battery cell may be used for, e.g., portable small-sized electronic devices, such as a mobile phone, a notebook, a computer, a camera, a camcorder, and the like. A second battery that is formed of a battery pack including a plurality of battery cells may be used for, e.g., a motor driving power supply for a high-output hybrid electric vehicle (HEV), an electric vehicle (EV), and the like.